Mr. Lipinski has asked several excellent questions regarding the
ferret's
digestive anatomy and conversely how it effects the ferret's diet.

Scientifically, a diet is that amount of nutrients in the proper
quantity,
quality and balance, feed to an animal in a palatable form, so that
in a
twenty-four hour period it will maintain or support its
physiological state.
Because ferrets have such a unique digestive system they are
strictly limited
as to what they can eat. As has been stated in many references,
ferrets are
obligate carnivores, meaning they must have a meat based diet daily.
This is
not a preference in selecting a food it is a must if the ferret is
to live.
Selecting a diet first and foremost must be on the basis of meat
content.
Many volumes have been written by numerous authors as well as myself
in great
detail on this subject. I will not cover selecting and evaluating a
diet
here.
Regarding MR. Lipinski's questions on the effect of the ferret's
metabolic
anatomy relative to what and how a ferret eats.
A ferret has no ceacum. Dogs, cats, humans and most other animals
have a
ceacum. In those animal, the ceacums is located at the point where
the small
intestines widen to become the large intestines. This location is
called the
ileocolic junction. The ceacum itself is a blind pouch which
functions to
provide some digestion of the complex carbohydrates, and fiber. It
contains
nonpathogenic, symbiotic bacteria which secrete enzymes in the
ceacum, which
in turn digest the fiber and complex carbohydrates. The rabbit and
horse
have a disproportionate sized ceacum relative to their body size and
most
other animals, which allows them to eat large quantities of fibrous
feedstuff
such as hay and grass. Neither of these animals nor any other
mammals
secrete fiber digesting enzymes, these are only secreted by the
bacteria in
the ceacum. On the other hand, ruminants, such as cattle, sheep,
goats,
deer, etc., have a specialized digestive system, which allows them
to digest
high fiber diets such as grass and hay even more efficiently than
the rabbit
or horse. This is because the have a large paunch called a rumen
which host
to billions of symbiotic bacteria and single cell microorganism
which in turn
secrete fiber digesting enzymes that then break down the fiber in
the food.
Back to the ferret. The lack of a ceacum limits the ferret in
eating fiber
containing foods. From our research we found that fiber should not
exceed
1.5% to optimize the digestibility of the whole diet. This is
another reason
why I recommend not feeding cat food or any other foods as the
primary diet
for the ferret if it contains more than 2% fiber.
The second anatomical difference between ferrets and other
carnivores, is the
short large intestine or colon. Ferrets do have colons but an
extremely
short one. It is approximately 10 cm (3.94 inches) long. This
proportionally is about 1/3 to 1/2 as long as a cats colon. The
ferret's
colon contains very little convolutions or folds which would aid in
the water
and nutrient recovery from digestion. The surface is almost smooth.
There
are very few bacteria in this area which is also contrary to most
other
animals which means the ferret cannot synthesize any B vitamins.
These two anatomical differences plays a major role in what the
ferret eats.
The rate of passage for food from the time the ferret eats till it
poops is
about 3 to 4 hours. This further dictates that high quality animal
protein
must be the major portion of the diet. Probioticts or Prebiotics
such as
yogurt, lactobacillus, etc., or yucca, fructo- oligosaccharides
(FOS) are
therefore non effective in the healthy ferret because the intestinal
track
does not support bacterial growth as does those of other animals.
This is a
major reason why holistic foods are a rip-off and have no
physiological
benefits in ferrets.
The ferret has a very specialized gut which has evolved eating meat
as its
primary protein and energy source. As Bob Church pointed out, the
wild
ancestors of the ferret, the polecat, also ate insects, eggs, and
many types
of small prey. There digestive system secrets very powerful
proteolytic and
lipolytic (protein and fat digesting) enzymes. They also secrete
some lipase
enzymes in the small intestine which digest the simple carbohydrates
and
sugars. However, their digestive system can be overwhelmed with
simple
carbohydrates such as sugar, dextrose, and fructose (fruit sugars)
if feed
foods or treats containing them. Fruits such as grapes, raisins,
bananas,
apples, cantaloupe contain both high levels of sugar as well as
fiber. This
is a double whammy for a ferret and should not be fed. A good
ferret diet
should contain at least 34 to 37% protein, 18 to 24% fat no more
than 1.5%
fiber and no more than 25% carbohydrates and no sugar. Of course
the major
protein sources should be from high quality chicken byproducts,
meat, eggs
and liver. Diets with gluten, soy or other complex vegetable
proteins cannot
be digested by the ferret and can even cause digestive problems.
Regarding
the effects of highly soluble carbohydrates such as sugar, or high
carbohydrate diets (35% or higher), I am not aware of any studies
which have
established the long term effect of their feeding. Knowing their
anatomy and
reviewing the data from our own research, I do not believe it would
be in
their best interest for the long term health considerations of the
ferret.
Sincerely,
DR Tom Willard